1. Field of the Invention
The present invention relates to an input device for inputting two-dimensional information, such as coordinates and directions on a screen, into a storage and processing apparatus such as a personal computer, and more particularly, to a mouse.
2. Description of the Related Art
As an input device for inputting two-dimensional information into a storage and processing apparatus such as a personal computer, a mouse, a trackball, a joy stick, and the like are widely used. With regard to the mouse, when the operator moves the mouse on an operation surface, such as a desk, a ball contained in a casing rotates, the direction and amount of rotation are mechanically detected, and two-dimensional information corresponding to the moving amount and direction of the mouse is given to the storage and processing apparatus.
Therefore, if the ball of the mouse does not rotate smoothly, two-dimensional information that the operator desires is not output from the mouse. In general, the ball is made of a material that produces large friction with the operation surface, such as rubber. The ball made of a material of this type is easy to rotate smoothly, while dust and dirt on the operation surface are prone to adhere onto the surface of the ball. If dust and dirt are deposited between the ball and a rotation detecting section, the rotation of the ball is not reliably transmitted to the rotation detecting section, and the input of desired two-dimensional information is impossible, for example, a cursor on the screen does not move no matter how the operator moves the mouse.
When desired two-dimensional information cannot be input as mentioned above, the operator cannot immediately know why the input trouble has occurred, that is, whether the input has been disabled due to unsmooth rotation of the ball, or due to the trouble caused in a wiring system or the storage and processing apparatus. Accordingly, when trouble occurs in the conventional mouse, the operator removes a cover plate mounted at the bottom of the casing of the mouse, and checks to see if dust and dirt are adhering onto the ball or the rotation detecting section. If dust and dirt are adhering, they are removed by cleaning.
It is, however, troublesome to remove the cover plate at the bottom of the casing and to perform checking and cleaning every time trouble of this type occurs. Even if no dust and dirt are adhering, the structure of the conventional mouse makes it difficult to actually verify that the ball can smoothly rotate in operation. Furthermore, in recent years, personal computers and the like have become widespread for home use, and have also been used by persons that are not accustomed to such apparatuses. Therefore, such persons cannot remedy trouble unless they discover that it is necessary to check the ball section. In addition, there is a demand that the cause of trouble be determined more easily.